Pulmonary Clinic Tests & Procedures
Pulmonary function tests are a series of tests, which evaluate how well your lungs are performing.
Staffed by Licensed Respiratory Care Practitioners, the pulmonary lab performs many tests that help physicians evaluate a patient’s lung health. “Pulmonary function tests”, usually called PFT’s are the most frequently ordered pulmonary lab tests. Different types of PFT’s can be performed depending on the age of the child. Each test requires a certain level of cooperation for the test to be successful and accurate. Generally, PFT’s are ordered within the following guidelines:
|8 & older
||spirometry every visit, lung volumes as needed
|6 & 7
||spirometry each visit
|3, 4 & 5
||spirometry as able (many this age cannot correctly perform test)
|up to 3
||infant pulmonary function testing
Infant Pulmonary Function testing is done in the main pulmonary lab. When patients are old enough to cooperate, they will be testing in either the pulmonary lab located on the second floor in the main hospital or the satellite pulmonary lab, which is accessible in the Sturgis building.
The Pulmonary Laboratory does several other tests to evaluate:
This test is performed while a patient sedated by a pediatric pulmonologist and is not available as part of a clinic visit. A bronchoscopy consists of inserting a long, thin tube (usually through the nose) through the upper airway into the lungs. The physician can look at the surface of the lungs and take sputum specimens. This test may help find an infection or other lung problem. A CF patient may never need a bronchoscopy. It is performed only when a problem persists that cannot be identified by other means.
The technician will teach your child a few different ways of breathing. First, your child’s baseline lung function will be tested. During this part your child will blow into a tube, using effort as if blowing out birthday candles. Next your child will breathe cold air through a special breathing circuit using a mouthpiece similar to what a scuba diver uses. The air will not feel cold on your child’s throat or mouth. After breathing in the cold air your child will repeat the first set of breathing tests to check for a change with the cold air. Your child will then be given a bronchodilator (medicine that helps open the small airways in the lungs). This medicine is given either as an inhaler or a nebulizer treatment. Some children may notice a faster heart rate for a short time after taking the medicine. The technician will then have your child repeat the first breathing test to check for any change with the medicine.
In some instances, the helium dilution study is used to evaluate lung volumes instead of the body box. It requires quiet breathing on a mouthpiece for 3-5 minutes followed by a full inspiration and expiration. This test may not provide the more specific results for some patients with CF. It is usually used for:
- Patient who have a difficult time tolerating body box study
- Comparison to body box study results as needed
Around 8 years of age, patients usually are able perform a more difficult test called body plethysmography which is often called “a body box study”. This nickname comes from the appearance of the equipment, which resembles a phone booth with a bench seat inside. The patient sits inside the box and breaths on a mouthpiece. Chest movements and changes in breathing pressures are measured, so the computer can calculate lung volumes. This test shows the total amount of air in the lungs and gives a more complete picture of a patients’ breathing function. This test takes about 20 minutes and will be performed at least once a year during annual visits.
Six Minute Walk Tests
This test is performed to determine how exercise affects your lung function. You will have a lung function test before and after you exercise to see if there is a change in lung function.
Spirometry (lung function test)and Bronchodilator Response
During Clinic: The most common PFT performed is basic “spirometry”. This test checks the volumes and flow rates the patient is capable of producing by forcing (blowing) air out of their lungs into a mouthpiece. The test results can be compared at each visit to determine if lung function is staying the same, improving, or getting worse. A nose clip is used to keep air from coming out of the nose, so all the air goes into the mouthpiece. Three consistent forced expirations are required for a good test. A respiratory therapist in the pulmonary lab area will coach and encourage the patient during the test to get the best effort. The test takes about 20 minutes. Sometimes, the test is repeated after giving a treatment with a bronchodilator (Albuterol) to see if breathing changes with the medicine. Spirometry can help evaluate if a change in therapy is needed at home.
During Admission: Patients admitted to the hospital perform PFT’s soon after admission and usually several more times before going home (depending on the length of stay in the hospital). This is one way to evaluate how well a patient is improving during the hospital stay and decide when they are well enough to go home.
(Note some patients report feeling mild-to-moderate discomfort in an area about one inch square on the forearm for five minutes during test while others report no discomfort at all during this five minutes period.) The most reliable way to diagnose CF is analysis of the sweat for amount of chloride (salt) it contains. (Note: It is important to have a sweat test using the method approved by the CF foundation for both collection and analysis. “Screening tests” may be unreliable.) The patient’s forearm is thoroughly cleaned and chemical called pilocarpine is placed on the forearm. Two small, battery-powered electrodes are attached. A small current (four mill amperes) from the electrodes forces the pilocarpine into the skin stimulating sweat glands to sweat in that spot on the forearm. Stimulation of the sweat gland takes five minutes. This sweat stimulation feels uncomfortable to some, but many people feel only a tingling sensation. Then a round, plastic disk is taped onto the arm and a piece of gauze is placed under it. The patient wears the gauze patch for 30 minutes to collect the sweat. The gauze is then removed and sent to the lab for analysis of the chloride content. Results of the sweat test are usually available on the date of service. Patients who are sent for a test by a physician outside of ACH must obtain the results from the ordering physician. Patients being seen in an ACH clinic can get results from ACH physician.
A sweat test result higher than 60 mEq/L is considered positive for cystic fibrosis and must be repeated before a diagnosis of CF can be made. Results between 40-60 mEq/L are considered inconclusive and must be repeated as well. Results lower than 40 mEq/L are negative and do not bear repeating.